Hollywood is in the midst of its meanest Oscar season battle in memory.

Sparked in part by the avalanche of late-year releases, which insiders believe has kept Academy voters from seeing many of the Oscar favorites, the bitter battle has seen some popular films slammed and some high-profile talent getting booed during public appearances.

The fact that many actors didn’t view all the Oscar favorites left them more dependent on whisper campaigns, insiders said.

Both the bad press and the poor public treatment of some A-listers were engineered by studios looking to slime a rival, several high-ranking Tinseltown insiders said in interviews.

The mudslinging seemed to reach a peak just ahead of Thursday’s deadline for Oscar voting.

“The campaigning is as bloody and as brutal as I’ve ever seen,” Nikki Finke, a reporter who has covered Hollywood for years, told The Post.

“Every studio gets down and dirty with this stuff,” Finke noted. “I’d like to think that Harvey Weinstein’s unseen hand is behind it, but everybody is behind it.”

One of the biggest targets of the mud-slinging is Paramount’s “The Wolf of Wall Street.”

“There is a concerted effort by LA people to denigrate the New York film in the race. It’s been done against [Martin Scorsese, the director] in the past.”

“12 Years a Slave” poster from Italy

In another late-year release, “12 Years a Slave,” some Academy members may be influenced by a marketing campaign in Italy, in which Brad Pitt appeared larger than life rather than the film’s star, Chiwetel Ejiofor, suggesting the movie was insensitive to race issues.

In many media reports, the Scorsese movie has been knocked as celebrating the excesses of Wall Street at a time when the economy is still in recovery. Other stories have pointed out that the film ignores the real victims of the fraud were grandmothers.

Heckling seems to be the hallmark of this year’s Oscar race.

A voter shouted “Shame on you,” to Scorsese at a screening, over the copious drugs and sex scenes.

Meanwhile a New York Critics Circle member allegedly described “12 Years a Slave” director Steve McQueen as an “embarrassing doorman.”

CBS Films kicked off a controversy over a full-page ad for “Inside Llewyn Davis,” which featured a tweet from New York Times film critic A.O. Scott that read: “You all keep fighting about Wolf of Wall St. and Am Hustle [American Hustle]. I’m gonna listen to the Llewyn Davis album again. Fare thee well, my honeys.”

The ad deleted references to the other movies.

Kyle Smith, film critic for The Post, even got draggedinto the ugly Oscar battle when Weinstein Co. took out print ads to dispute Smith’s view that its “Philomena” is anti-Catholic.

The reason for the pre-Oscar battle is clear: money.

An Oscar win can add tens of millions of dollars to a studio’s coffers.

One Hollywood veteran said that if people think the battling was ugly now, just wait until Jan. 16.